Elastomer blend composition of a sulfonated EPDM terpolymer and a polystyrene resin

ABSTRACT

This invention relates to heterogeneous elastomeric blends having improved rheological properties of a major portion of a neutralized sulfonated elastomeric polymer with a minor portion of a polystyrene thermoplastic resin or a neutralized sulfonated polystyrene resin and mixtures thereof. Both the sulfonated elastomeric polymer and the sulfonated thermoplastic resin have about 0.2 to about 10.0 mole percent of SO 3  H groups, at least 90% of which are neutralized with an organic amine.

This is a division, of application Ser. No. 791,162, filed Apr. 26,1977.

FIELD OF THE INVENTION

This invention relates to heterogeneous elastomeric blends havingimproved rheological properties of a major portion of a neutralizedsulfonated elastomeric polymer with a minor portion of a polystyrenethermoplastic resin or a neutralized sulfonated polystyrene resin andmixtures thereof. Both the sulfonated elastomeric polymer and thesulfonated thermoplastic resin have about 0.2 to about 10.0 mole percentof SO₃ H groups, at least 90% of which are neutralized with an organicamine.

BACKGROUND OF THE PRIOR ART

U.S. Pat. No. 3,642,728, herein incorporated by reference, teaches a newclass of sulfonated polymers which are derived from polymers containingolefinic unsaturation, especially elastomeric polymers, e.g. butyl andethylenepropylene terpolymers. These materials may be neutralized withorganic amines or basic materials selected from Groups I, II, III, IV,V, VI-B, VII-B and VIII and mixtures thereof of the Periodic Table ofElements. These materials, especially the butyl and theethylene-propylene terpolymer (EPDM) derivatives, may broadly beclassified as thermoelastomers, that is these materials may be processedat high temperatures by use of shear force in the presence of selectedpolar additives and yet at the temperature of use, e.g. roomtemperature, the materials, through the association of the sulfonategroup behave as cross-linked elastomers. Thus, these materials representone form of reprocessable elastomers, which are very desirable inindustry.

However, although these materials are commercially useful, the meltviscosity even at very high temperature tends to be sufficiently high asto preclude the use of conventional plastic fabrication techniques.Thus, the very purpose for which these compounds are derived is notadequately fulfilled. In this invention, it has unexpectedly beendiscovered that decreased melt viscosity may be obtained by combiningthese polymers with a minor portion of a polystyrene thermoplastic resinor a sulfonated polystyrene in a heterogeneous polymer blend. Further,it has been unexpectedly discovered that the tensile properties of theseblends, as measured at room temperature, can be substantially improvedas compared to the sulfonated elastomers alone.

The sulfonated elastomers described in U.S. Pat. No. 3,647,728, hereinincorporated by reference, when used as gums possess a relatively lowlevel of rigidity or stiffness which yields rather limp materialsincapable of supporting themselves when prepared in thin sections. Thisis a major limitation, if one desires to prepare dimensionally stableparts, e.g. automotive or appliance applications. It is known in the artthat stiffness of elastomers may be increased by the combination ofcarbon black or inorganic material such as clays, calcium carbonate orsilicates, etc. However, these materials, while increasing the hardness,further deteriorate the melt viscosity of the above-described ionicelastomers. Thus, systems which at best have borderline processabilityeven at very low metal sulfonate levels further deteriorate in theirflow behavior and thus cannot be processed at all. It has unexpectedlybeen discovered that in the compositions of the instant invention,wherein minor amounts of the unsulfonated or sulfonated polystyrene arecombined with the sulfonated elastomers described above, result inincreased tensile modulus at room temperature.

Thus, this invention teaches compositions of matter which representsignificant improvement over the prior art in that low melt viscosity isobtained at no loss in tensile properties.

The present application is related to two other filed applications Ser.Nos. 514,502, now U.S. Pat. No. 3,905,586 and 514,512, now U.S. Pat. No.3,923,370, herein incorporated by reference. These two applications,which have issued, are related to elastomeric blends of a crystallinepolyolefinic resin and a neutralized sulfonated elastomeric blends.These blends are of a homogeneous nature, wherein the crystallinepolyolefinic resin appears completely soluble in the sulfonatedelastomeric polymer at elevated temperatures. The melt rheology andtensile properties of these homogeneous blends are improved as comparedto the unmodified sulfonated elastomeric polymer due to theplasticization of the polymeric backbone of the elastomeric polymer.However, the blending of an inorganic filler with neutralized sulfonatedelastomeric polymer creates a heterogeneous blend, wherein therheological and physical properties are adversely affected due toincomplete interfacial bonding between the inorganic particles and theelastomeric matrix. Blends of a neutralized sulfonated elastomericpolymer and a polystyrene thermoplastic resin or a sulfonatedpolystyrene thermoplastic resin, wherein the thermoplastic resin is at aconcentration level in excess of 20 parts per hundred by weight based on100 parts of the neutralized sulfonated elastomeric polymer, exhibit ageneral deterioration in physical properties due to the manifestation ofgross incompatibility. Surprisingly, it has been found that theincorporation of the polystyrene or sulfonated polystyrene at aconcentration level of below about 20 parts per hundred by weightresults in compositions exhibiting both improved physical andrheological properties.

SUMMARY OF THE INVENTION

It has been unexpectedly discovered that novel elastomeric heterogeneousblend compositions comprising a major portion of a sulfonatedelastomeric polymer having at least 90% of the SO₃ H groups combinedwith an organic amine and a minor portion of a polystyrene thermoplasticresin or a neutralized sulfonated polystyrene and mixtures thereof showunexpectedly improved melt viscosity properties and improved roomtemperature physical properties (as compared to the sulfonatedelastomer) itself. More particularly, the sulfonated elastomer isderived from an EPDM terpolymer (i.e., a terpolymer of ethylene,propylene, and a small amount, e.g., <10 mole % of a diene monomer).

Accordingly, it is an object of my present invention to provideelastomeric heterogeneous blend compositions of a neutralized sulfonatedelastomeric polymer and a polystyrene thermoplastic resin or asulfonated polystyrene, wherein these heterogeneous blend compositionshave both improved physical and rheological properties as compared tothe unmodified neutralized sulfonated elastomeric polymer.

A further object of my present invention is to provide a unique andnovel process for the formation of these elastomeric heterogeneous blendcompositions having improved physical and rheological properties.

GENERAL DESCRIPTION OF THE INVENTION

This present invention relates to unique and novel heterogeneous blendcompositions of a neutralized sulfonated elastomeric polymer and apolystyrene thermoplastic resin or a sulfonated polystyrene, wherein thepolystyrene is microdispersed as discrete particles in the neutralizedsulfonated elastomeric polymer matrix. These heterogeneous blendcompositions exhibit improved physical and rheological propertiesthereby permitting these heterogeneous blend compositions to beprocessed by conventional plastic fabricating techniques such asinjection molding or extrusion.

Various chemical additives can be incorporated into the heterogeneousblend compositions for modification of a particular physical property.

The EPDM terpolymers are low unsaturated polymers having about 0.1 toabout 10 mole % olefinic unsaturation defined according to thedefinition as found in ASTM-D-1418-64 and is intended to meanterpolymers containing ethylene and propylene in the backbone and adiene in the side chain. Illustrative methods for producing theseterpolymers are found in U.S. Pat. No. 3,280,082, British Pat. No.1,030,289 are French Pat. No. 1,386,600, which are incorporated hereinby reference. The preferred polymers contain about 40 to about 80 wt. %ethylene and about 1 to about 10 wt. % of a diene monomer, the balanceof the polymer being propylene. Preferably the polymer contains about 50to about 60 wt. % ethylene, e.g. 50 wt. % and about 2.6 to about 9.0 wt.% diene monomer, e.g. 5.0 wt. %. The diene monomer is preferably anonconjugated diene.

Illustrative of these nonconjugated diene monomers which may be used inthe terpolymer (EPDM) are 1,4 hexadiene, dicyclopentadiene, ethylidenenorbornene, methylene norbornene, propenyl norbornene, and methyltetrahydroindene. The EPDM terpolymer has a number average molecularweight of about 10,000 to about 200,000, more preferably of about 15,000to about 100,000, most preferably of about 20,000 to about 60,000. TheMooney viscosity of the EPDM terpolymer at (1+8) min. at 212° F. isabout 5 to about 90, more preferably about 10 to about 50, mostpreferably about 15 to about 25. The Mv of the EPDM terpolymer ispreferably below about 350,000 and more preferably below about 300,000.The Mw of the EPDM terpolymer is preferably below about 500,000 and morepreferably below about 350,000.

A typical EPDM terpolymer is Vistalon 3708 (Exxon Chemical Co.).Vistalon 3708 is a terpolymer having a Mooney viscosity at (1+8) min. at212° F. of about 45-55 and having about 64 wt. % ethylene, about 3.3 wt.% of 5-ethylidene-2-norbornene, and having about 53 wt. % of ethylene,about 3.5 wt. % of 1,4 hexadiene, and about 43.5 wt. % of propylene.

The polystyrene thermoplastic resins of the present invention areselected from the group consisting essentially of polystyrene,poly-t-butyl-styrene, polychlorostyrene, polyalpha methyl styrene or co-or terpolymers of the aforementioned with acrylonitrile or vinyltoluene.

The polystyrene thermoplastics suitable for use in the practice of theinvention have a glass transition temperature from about 90° C. to about150° C., more preferably about 90° C. to about 140° C. and mostpreferably about 90° C. to about 120° C. These polystyrene resins have aweight average molecular weight of about 5,000 to about 500,000, morepreferably about 20,000 to about 350,000 and most preferably about90,000 to about 300,000. These base polystyrene thermoplastic resins canbe prepared directly by any of the known polymerization processes. Theterm "thermoplastic" is used in its conventional sense to mean asubstantially rigid (flexus modulus>10,000 psi) material capable ofretaining the ability to flow at elevated temperatures for relativelylong times.

The preferred polystyrene thermoplastic resin is a homopolymer ofstyrene having a number average molecular weight of about 180,000, andan intrinsic viscosity in toluene of about 0.8. These polymers arewidely available commercially in large volume. A suitable material isDow Polystyrene 666 which affords a suitable molecular weight.

In carrying out the invention, the EPDM terpolymer or the polystyrenethermoplastic resin is dissolved in a nonreactive solvent such aschlorinated aromatic hydrocarbon, a chlorinated aliphatic hydrocarbon,an aromatic hydrocarbon, of an aliphatic hydrocarbon such aschlorobenzene, benzene, toluene, xylene, cyclohexane, pentane, hexane,or heptane. The preferred solvents is carbon tetrachloride for both theEPDM terpolymer and the polystyrene thermoplastic resin. A sulfonatingagent is added to the solution of the EPDM terpolymer and nonreactivesolvent at a temperature of about -100° C. to about 100° for a period oftime of about 5 to about 60 minutes, more preferably at room temperaturefor 45 minutes, and most preferably at room temperature for 30 minutes.Typical sulfonating agents are described in U.S. Pat. Nos. 3,642,728 and3,836,511, incorporated herein by reference. These sulfonating agentsare selected from an acyl sulfate, a mixture of sulfuric acid and anacid anhydride of a complex of a sulfur trioxide donor and a Lewis basecontaining oxygen, nitrogen, or phosphorous. Typical sulfur trioxidedonors are SO₃, chlorosulfonic acid, fluorosulfonic acid, sulfuric acid,oleum, etc. Typical Lewis bases are: dioxane, tetrahydrofuran,phosphorous acid, phosphonic acid, triethylphosphate, trimethylamine, orpiperidine. The most preferred sulfonation agent for the polystyrenethermoplastic is an acyl sulfate selected from the group consistingessentially of benzoyl, acetyl, propionyl or butyryl acetate. The acylsulfate can be formed in situ in the reaction medium or pregeneratedbefore its addition to the reaction medium. A preferred acyl sulfate isacetyl sulfate. The most preferred sulfonation agent for the EPDMterpolymer is a complex of sulfur trioxide and dioxane. It should bepointed out that neither the sulfonating agent nor the manner ofsulfonation is critical, provided that the sulfonating method does notdegrade the polymeric backbone. The reaction is quenched with analiphatic alcohol being selected from methanol, ethanol, n-propanol orisopropanol, with an aromatic phenol, or with water. The acid form ofthe sulfonated EPDM terpolymer a polystyrene thermoplastic resin hasabout 10 to about 100 meq. of SO₃ H groups per 100 grams of polymer,more preferably about 15 to about 40; and most preferably about 20 toabout 35. The mole percent of SO₃ H groups is about 0.2 to about 20,more preferably about 0.2 to about 10.0. The meq. of SO₃ H/100 grams ofpolymer was determined by both titration of the polymeric sulfonic acidand Dietert Sulfur analysis. In the titration of the sulfonic acid thepolymer was dissolved in a solvent consisting of 95 parts of toluene and5 parts of methanol at a concentration level of 50 grams per liter ofsolvent. The acid form is titrated with ethanolic sodium hydroxide to anAlizarin Thymolphthalein endpoint.

The solution of the acid form of the sulfonated EPDM terpolymer and thesulfonated polystyrene thermoplastic resin are mixed together andneutralized with a neutralizing agent. Neutralization of the acid formsof the sulfonated EPDM terpolymer and the sulfonated polystyrenethermoplastic resin is done by the addition of an organic amine to forman amine salt.

The organic amines used to form the ionic bonds can be primary,secondary, or tertiary amines, wherein the organic radicals are C₁ toC₃₀ alkyl, phenyl, aralkyl or alkaryl. More preferably, the organicradical is a phenyl, C₁ to C₁₀ alkyl, C₇ to C₁₀ alkylaryl or C₇ to C₁₀aralkyl. Illustrative of such amines are anhydrous piperazine,triethylamine, tri-n-propylamine and tetraethylene-pentamine, piperazineand tri-n-propylamine.

Guanidines are preferred neutralizing agents for the sulfonic acidgroups to produce ionic sites. The preferred guanidines are guanidine orsubstituted guanidines, wherein the substituent organic radicals are C₁to C₃₀ alkyl, phenyl, aralkyl, or alkaryl. Illustrative of suchguanidines are tetra-methyl guanidine, di-phenyl guanidine anddi-ortho-tolyl guanidine.

The preferred neutralizing agent for the acid forms of the sulfonatedEPDM terpolymer and sulfonated polystyrene thermoplastic resin isdi-ortho-tolyl guanidine (DOTG). Sufficient meq. of the metal salt ofthe carboxylic acid or the organic amine or added to the solution of theacid forms of the sulfonated EPDM terpolymer and the sulfonatedpolystyrene thermoplastic to effect at least about 1 to about 100%neutralization of the acid groups, more preferably about 50 to about100%, and most preferably about 90 to about 100%.

The mixture of the neutralized sulfonated EPDM terpolymer and theneutralized sulfonated polystyrene thermoplastic resin is isolated fromsolution by steam stripping to give a heterogeneous blend of theneutralized sulfonated polystyrene microdispersed in the neutralizedsulfonated elastomeric polymer.

Alternatively, a polystyrene dissolved in the carbon tetrachloride resincan be added to the solution of the acid form of the sulfonatedelastomeric polymer. The DOTG is added to the solution to neutralize theacid form of sulfonated elastomeric polymer. The mixture of thepolystyrene thermoplastic resin and the neutralized sulfonatedelastomeric polymer are isolated from solution by steam stripping togive a heterogeneous blend of the polystyrene thermoplastic resinmicrodispersed in the neutralized sulfonated elastomeric polymer.

In order to maximize the compatability of the polystyrene or sulfonatedpolystyrene into the neutralized sulfonated elastomeric polymer, it isnecessary to employ a solution process. Intensive mixing process such asa Banbury extruder or a two-roll mill results in compositions, whereinthe physical and rheological properties have not been maximized.

The polystyrene thermoplastic resin or the sulfonated polystyrene is aminor proportion of the heterogeneous blend at a concentration level ofabout 1 to about 20 parts per hundred based on 100 parts of theneutralized sulfonated elastomeric polymer, more preferably about 2 toabout 15; and most preferably about 3 to about 10.

Various chemical additives can be incorporated in the blend such asfillers and oils. These chemical additives are incorporated into theheterogeneous elastomeric blend by a conventional dry blend two-rollmill technique, or by a conventional intensive mixing process such as ahigh steam batch Banbury or a continuous twin screw extruder. Theconcentration level of these additives is from about 25 to about 300parts per hundred based on 100 parts of the neutralized sulfonatedelastomeric polymer, more preferably about 30 to about 250; and mostpreferably about 50 to about 200.

The fillers employed in the present invention are selected from carbonblacks, talcs, ground calcium carbonate, water precipitated calciumcarbonate, or delaminated, calcined or hydrated clays and mixturesthereof. Examples of carbon black are oxides, acetylinics, lamp, furnaceor channel blacks. Typically these fillers have a particle size of about0.03 to about 15 microns, more preferably about 0.5 to about 10, andmost preferably about 2 to about 10. The oil absorption of the filler asmeasured by grams of oil absorbed by 100 grams of filler is about 10 toabout 70, more preferably about 10 to about 50 and most preferably about10 to about 30. Typical fillers employed in this invention areillustrated in Table 1.

The oils employed in the present invention are non-polar backboneprocess oils having less than about 3.5 wt. % polar type compounds asmeasured by molecular clay gel analysis. These oils are selected fromparaffinics ASTM Type 104B as defined in ASTM-D-2226-70, aromatic ASTMType 102 or naphthenics ASTM 104A, wherein the oil has a flash point bythe Cleveland open cup of at least 350° F.; a pour point of less than40° F., a viscosity of about 70 to about 3000 s.s.u.'s and a numberaverage molecular weight of about 300 to about 1000, more preferablyabout 400 to about 75°. The preferred oils are napthenics. Table IIillustrates typical oils encompassed by the scope of this invention.

                                      TABLE 1                                     __________________________________________________________________________                      Oil Absorption Specific                                                                           Avg. Particle                            Filler      Code #                                                                             grams of oil/100 grams of filler                                                             Gravity                                                                            Size Micron                                                                          pH                               __________________________________________________________________________    calcium carbonate ground                                                                        15             2.71        9.3                              calcium carbonate                                                             precipitated      35             2.65 .03-.04                                                                              9.3                              delaminated clay  30             2.61 4.5    6.5-7.5                          hydrated clay                    2.6  2      4.0                              calcined clay     50-55          2.63 1      5.0-6.0                          magnesium silicate (talc)                                                                       60-70          2.75 2      9.0-9.5                          __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________                 Viscosity                                                                              %    %    %                                             Type Oil                                                                            Oil Code #                                                                           ssu 100° F.                                                                  Mn Polars                                                                             Aromatic                                                                           Saturates                                     __________________________________________________________________________    Paraffinic                                                                          Sunpar 115                                                                           155   400                                                                              0.3  12.7 87.0                                          Paraffinic                                                                          Sunpar 180                                                                           750   570                                                                              0.7  17.0 82.3                                          Paraffinic                                                                          Sunpar 2280                                                                          2907  720                                                                              1.5  22.0 76.5                                          Aromatic                                                                            Flexon 340                                                                           120   -- 1.3  70.3 28.4                                          Naphthenic                                                                          Flexon 765                                                                           506   -- 0.9  20.8 78.3                                          Naphthenic                                                                          Flexon 580                                                                           1855  -- 3.3  47.0 49.7                                          __________________________________________________________________________

Alternatively, the oils can be incorporated in the elastomericheterogeneous blend by the addition of the oil under agitation to thesolution of the mixture of the neutralized sulfonated elastomericpolymer and the polystyrene or sulfonated polystyrene prior to the steamstripping step.

Compression molded pads were made of the heterogeneous blends at 350° F.for 5 min. wherein the sample pads were 2"×2"×0.040". Micro specimenswere cut out from the pads for tensile, hardness, compression set, andstress relaxation measurements.

Tensile measurements were made by an Instron Tester at the crossheadspeed of 2 in./min. using micro-dumbbell specimens. Melt rheologicalproperties were measured by an Instron Capillary Rheometer with a0.050"D×1", L, 90° entrance angle capillary.

The application for the heterogeneous blends of this invention arediverse. The blends have excellent injection molding and extrusionproperties. For example, injection molded shoe soles may be preparedfrom the instant blends because of their excellent abrasion resistanceand flex fatigue properties which are highly desired in suchapplication. Injection molded parts for automotive applications may beprepared from the blends of this invention, e.g., automobile sightshields, flexible bumpers, grill parts, etc. It is readily apparent tothose skilled in the art that the properties, such as rigidity, can bevaried widely depending on the level of the polystyrene or sulfonatedpolystyrene incorporated in the sulfonated elastomeric polymer, thusfabrication of rigid or semiflexible articles from the instant blends iscontemplated. Articles from the blends of the instant invention may alsobe prepared by extrusion techniques. For example, garden hose, havingoutstanding strength in combination with light weight is oneapplication. The electrical properties of these materials also allow theuse of the instant blends as insulation for wire. Insulation preparedfrom rubber or polyethylene often requires a curing or vulcanizationstep to obtain optimum properties. The blends of this invention haveexcellent physical properties, and excellent electrical propertieswithout the need for any curing step. The fact that chemical curing isnot required permits a relatively high speed extrusion operation whichare not feasible with those systems requiring a curing step.

Other fabrication processes for these materials include vacuum forming,flow molding, slit extrusion, profile extrusion and similar operations.The wide versatility, from a fabrication viewpoint, permits the use ofthese blends in film, containers such as bottles, oriented sheet,fibers, especially oriented monofilament, packaging, appliance housing,floor mats, carpet backing, toys, sporting goods such as swim fins, facemasks, and similar applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention may be understood withreference to the following detailed description of an illustrativeembodiment of the invention taken together with the accompanyingdrawings in which:

FIG. 1 illustrates a graph of gum tensile properties at room temperatureand the effect of sulfonation on an EPDM terpolymer;

FIG. 2 illustrates a graph of gum tensile properties at 200° C.;

FIG. 3 illustrates a graph of stress relaxation as a function oftemperature;

FIGS. 4 and 5 illustrates a graph of the rheological properties of asulfo-EPDM at 200° C.;

FIG. 6 illustrates a graph of the tensile properties of a sulfo-EPT(EPDM) at room temperature;

FIG. 7 illustrates a graph of the tensile properties of sulfo-EPT (EPDM)compound at room temperature;

FIG. 8 illustrates a graph of the tensile properties of a sulfo-EPT(EPDM) gum at room temperature;

FIG. 9 illustrates a graph of the tensile properties of a sulfo-EPT(EPDM) compound at room temperature;

FIG. 10 illustrates a graph of the tensile properties of the sulfo-EPT(EPDM) gum at room temperature;

FIG. 11 illustrates a graph of the tensile properties of the sulfo-EPT(EPDM) compound at room temperature;

FIG. 12 illustrates a graph of the tensile properties of the sulfo-EPT(EPDM) gum at room temperature as effected by the sulfonation level of apolystyrene; and

FIG. 13 illustrates a graph of the tensile properties of the sulfo EPT(EPDM) gum at room temperature as effected by the sulfonation level of apolystyrene.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The advantages of the unique and novel elastomeric heterogeneous blendcompositions and the unique and novel process for the formation of thesecompositions can be more readily appreciated by reference to thefollowing examples, tables, and figures.

EXAMPLE I PREPARATION OF AN ACID FORM OF A SULFONATED EPDM TERPOLYMER

To a solution of 90 grams of EPDM terpolymer (Vistalon 3708-ExxonChemical Co.) in 3 liters of carbon tetrachloride at 50° C. was added asolution of a sulfonating agent which was formed at 10° from 141 ml. ofmethylene chloride, 2.4 ml. of sulfur trioxide, and 5 ml. of dioxane.Sulfonation was terminated after 30 min. by quenching with methanol. Theacid form of the sulfonated EPDM terpolymer had 0.8 mole percent of SO₃H groups/100 grams of terpolymer.

EXAMPLE II PREPARATION OF AN ACID FORM OF A SULFONATED POLYSTYRENE RESIN

To a solution 20.8 grams of a polystyrene resin having an Mw of 287×10³(Styron 666) in 100 ml. of carbon tetrachloride at 50° C. was added asolution of a sulfonating agent which was formed at 10° C. from 4.762ml. of ethylene dichloride, 0.905 ml. of anhydrous acetic anhydride and0.333 ml. of 96.5% concentrated sulfuric acid and sulfonation wasterminated after 60 min. by quenching with methanol. The acid form ofthe sulfonated polystyrene resin had 3.0 mole percent of SO₃ Hgroups/grams of polystyrene resin. Sulfonated polystyrene resins havingan Mw of 93×10³ were also prepared, wherein the mole percent of SO₃ Hwas 3.0 or 6.0.

EXAMPLE III PREPARATION OF ELASTOMERIC BLEND COMPOSITIONS

To the quenched solution of the sulfonated EPDM terpolymer, preparedaccording to Example I, was added a solution of polystyrene resindissolved in carbon tetrachloride having an Mw of 93×10³ or 287×10³. Theresultant blended solution was neutralized at room temperature for 30min. with di-ortho-tolyl guanidine (DOTG). The elastomeric blendcompositions were recovered from solution by steam stripping.

Alternatively, to the quenched solution of the sulfonated EPDMterpolymer prepared according to Example I was added the solutions ofExample II of the acid form of the sulfonated polystyrene resin havingan Mw of 287×10³ or 93×10³. The resultant blended solution wasneutralized at room temperature for 30 minutes with di-ortho-tolylguanidine. The elastomeric blend compositions were isolated fromsolution by steam stripping.

The elastomeric blend compositions were compounded on a hot micro-rubbermill. Sample pads of 2"×2"×0.040" were molded at 35° F. for 5 min.Micro-specimens were cut out from the pads for tensile hardness,compression set and stress relaxation measurements.

Table III illustrates the formulas for these blend compositions andtheir physical properties as compared to an unsulfonated EPDM 3708terpolymer, a sulfonated EPDM 3708 terpolymer, and Kraton 101.

                                      TABLE III                                   __________________________________________________________________________    ELASTOMERIC BLEND COMPOSITIONS                                                wt. % of                                                                      sulfonated        wt. % of                                                    EPDM ter-         sulfonated                                                  polymer           polystyrene        Compression Set                                                                         Other                          0.8 mole %                                                                            Sample                                                                            wt. % of                                                                            3.0 mole %                                                                            --Mw  Shore A                                                                            ASTM-R    Elastomeric                    of SO.sub.3 . DOTG                                                                    #   polystyrene                                                                         of SO.sub.3 . DOTG                                                                    polystyrene                                                                         Hardness                                                                           RT   40° C.                                                                      Resin                          __________________________________________________________________________    100     1-1 --    --      --    73.0 43.5 76.9                                90      1-2 10    --      287 × 10.sup.3                                                                74.0 48.8 100                                 90      1-3 --    10      287 × 10.sup.3                                                                73.0 39.9 100                                 80      1-4 20    --      287 × 10.sup.3                                                                80.0 52.2 100                                 80      1-5 --    20      287 × 10.sup.3                                                                76.0 46.2 100                                 90      1-6 10    --       93 × 10.sup.3                                                                76.0 43.0 77.1                                90      1-7 --    10       93 × 10.sup.3                                                                80.0 39.3 77.7                                --      1-8 --    --      --    65.0 39.0 84.9                                --      1-9 --    --      --    63.0 41.0 61.0 EPDM 3708                                                                     Kraton 101                     __________________________________________________________________________

Sulfonation of EPDM 3708 improves the tensile properties as shown inFIG. 1 as compared to unsulfonated EPDM 3708; however, sulfonation andneutralization severely deteriorates the rheological properties of EPDMas shown in FIG. 2. The neutralized sulfonated EPDM 3708 has very poorflow stability manifested by melt fracture at a low shear rate of 15sec⁻¹ and about 3 times as high viscosity at 200° C. as that ofunsulfonated EPDM 3708. The hardness as seen in Table I of the EPDMterpolymer increases upon sulfonation and neutralization. The additionof 10 percent of polystyrene having an Mw of 287×10³ or sulfonatedpolystyrene having an Mw of 287×10³ does not change the hardness.However, the addition of either 10% of sulfonated or unsulfonatedpolystyrene having an Mw of 93×10³ increases the hardness. Increasingthe wt. % of the sulfonated or unsulfonated polystyrene increasesslightly the hardness. The addition of the sulfonated or unsulfonatedpolystyrene has little effect on the compression set, wherein thecompositions with sulfonated polystyrene has somewhat lower compressionset than samples from unsulfonated polystyrene.

FIG. 3 shows the effect of the sulfonated polystyrene on the equilibriumstress relaxation modulus of sulfonated EPDM 3708 as a function oftemperature. Ten percent of sulfonated polystyrene has no effect on theequilibrium stress relaxation modulus of the sulfonated EPDM 3708.

FIGS. 4 and 5 show the improvements in the rheological properties of theDOTG neutralized sulfonated EPDM 3708 by the addition of the sulfonatedor unsulfonated polystyrene. In both cases, the viscosity is reduced andthe flow stability is improved. FIGS. 4 and 5 also show that therheological properties are uneffected by changes in the Mw of thesulfonated or unsulfonated polystyrene.

FIGS. 6-11 show the effect on tensile properties of the addition of thesulfonated or unsulfonated polystyrene to the sulfonated EPDM 3708matrix. The sulfonated polystyrene appears to improve the tensileproperties better than does the unsulfonated polystyrene.

FIGS. 12 and 13 show the effect of the sulfonation level of thepolystyrene on the tensile properties of the blended elastomericcomposition. Six mole percent sulfonated polystyrene gives somewhatinferior tensile properties as compared to 3 mole percent sulfonatedpolystyrene at the same loading.

EXAMPLE IV

The compositions of Example III including the sulfonated EPDM 3708 wereblended according to the following formula and compounded on a micro-tworoll rubber mill to give extended elastomeric blend compositions.

    ______________________________________                                                           wt. percent                                                ______________________________________                                        Blend Compositions of Example III                                                                  28.57                                                    Flexon Oil 580 (Exxon Chemical Co.)                                                                28.57                                                    HAF Carbon Black (Cabot Corp.)                                                                     42.86                                                    ______________________________________                                    

Sample pads of 2"×2"×0.040" were molded at 350° F. for five min. andmicro-specimens were cut out for physical testing.

Tables III and IV clearly show that the incorporation of the filler andoil generally increases the hardness and compression set for theelastomeric blend compositions of the neutralized sulfonated EPDM 3708and either the neutralized sulfonated or unsulfonated polystyrene.

FIGS. 7, 9 and 10 show the tensile properties for the extendedelastomeric blend compositions that the tensile properties are improvedby the addition of either neutralized sulfonated or unsulfonatedpolystyrene, wherein the neutralized sulfonated polystyrene seems to besomewhat more effective.

The elastomeric blend compositions prepared by the improved unique andnovel process of this invention can be fabricated by conventional rubberfabricating techniques into a number of useful articles. For example,film, washer hose and radiator hose have been made by an extrusionprocess.

Since, many modifications of this invention may have been made withoutdeparting from the spirit or scope of the invention thereof, it is notintended to limit the scope or spirit to the specific examples thereof.

                                      TABLE IV                                    __________________________________________________________________________    ELASTOMERIC BLEND COMPOSITIONS                                                EXTENDED WITH FILLER AND OIL                                                  wt. % of                                                                      sulfonated        wt. % of                                                    EPDM ter-         sulfonated                                                  polymer           polystyrene        Compression Set                          0.8 mole %                                                                            Sample                                                                            wt. % of                                                                            3.0 mole %                                                                            Mw    Shore A                                                                            ASTM-R                                   of SO.sub.3 . DOTG                                                                    #   polystyrene                                                                         of SO.sub.3 . DOTG                                                                    polystyrene                                                                         Hardness                                                                           RT   40° C.                       __________________________________________________________________________    100     2-1 --    --      --    81   100  100                                 90      2-2 10    --      287 × 10.sup.3                                                                85   100  100                                 90      2-3 --    10      287 × 10.sup.3                                                                83   80.7 100                                 80      2-4 20    --      287 × 10.sup.3                                                                87   100  100                                 80      2-5 --    20      287 × 10.sup.3                                                                85   100  100                                 90      2-6 10    --       93 × 10.sup.3                                                                72   71.5 100                                 90      2-7 --    10       93 × 10.sup.3                                                                81   87.1 96.3                                __________________________________________________________________________

What is claimed is:
 1. A process for forming a heterogeneous elastomericblend composition, which comprises the following steps:(a) dissolving athermoplastic resin selected from the group consisting of polystyrene,poly alpha methylstyrene, poly t-butylstyrene or polyhalo-styrene in anon-reactive solvent to form a first solution; (b) dissolving an EPDMterpolymer in said non-reactive solvent to form a second solution; (c)sulfonating said EPDM terpolymer in said second solution with a suitablesulfonating agent to form an acid form of a sulfonated EPDM terpolymer,said acid form having about 0.2 to about 10.0 mole percent of sulfonategroups; (d) quenching said second solution; (e) blending said firstsolution into said second quenched solution to form a mixture of saidthermoplastic resin and said acid form of said sulfonated elastomericpolymer in said blended solutions; (f) neutralizing with a basicmaterial said acid form of said sulfonated EPDM terpolymer in saidblended solutions; and (g) steam stripping said blended solutions toremove the elastomeric blend composition, said blend compositioncomprising said neutralized sulfonated EPDM terpolymer and about 1 toabout 20 parts per hundred by weight of said thermoplastic resin basedon 100 parts by weight of neutralized sulfonated EPDM terpolymer.
 2. Aprocess according to claim 1, further comprising sulfonation of saidthermoplastic resin in said first solution to form an acid form of asulfonated thermoplastic resin, said acid form having about 0.2 to about10.0 mole percent sulfonate groups; and neutralizing with said basicmaterial said acid form of said sulfonated thermoplastic resin inconjunction with said acid form of said sulfonated EPDM terpolymer insaid blended solutions.
 3. A process according to claim 1, wherein saidthermoplastic resin is polystyrene.
 4. A process according to claim 2,wherein said thermoplastic resin is polystyrene.
 5. A process accordingto claim 1, wherein said non-reactive solution is a chlorinatedaliphatic hydrocarbon.
 6. A process according to claim 1, wherein saidEPDM terpolymer consists essentially of about 40 to about 65 wt. % ofethylene, of about 10 to about 53 wt. % of propylene, and of about 2 toabout 10 wt. % of a non-conjugated diene.
 7. A process according toclaim 6, wherein said non-conjugated diene is selected from the groupconsisting essentially of 1,4 hexadiene, dicyclopentadiene, alkydinesubstituted norbornene, methylene norbornene, or tetrahydroindene.
 8. Aprocess according to claim 6, wherein said non-conjugated is5-ethylidene-2-norbornene.
 9. A process according to claim 1, whereinsaid basic material is an organic amine.
 10. A process according toclaim 9, wherein said organic amine is di-ortho-tolyl guanidine.
 11. Aprocess according to claim 2, wherein said basic material is an organicamine.
 12. A process according to claim 11, wherein said organic amineis di-ortho-tolyl guanidine.
 13. A process according to claim 1, whereinsaid thermoplastic resin is at a concentration level in said blendcomposition of about 1 to about 20 parts per hundred by weight based on100 parts of said neutralized sulfonated EPDM terpolymer.
 14. A processaccording to claim 2, wherein said neutralized sulfonated thermoplasticresin in said blend composition is at a concentrate level of about 1 toabout 20 parts per hundred by weight based on 100 parts of saidneutralized sulfonated EPDM terpolymer.
 15. A process according to claim1, wherein said blend composition further includes a process oil, saidprocess oil being selected from the group consisting essentially ofnaphthenics, aromatics, or paraffinics.
 16. A process according to claim15, wherein said blend composition further includes a filler, saidfiller being selected from the group consisting essentially of carbonblacks, talc, clays or calcium carbonate, and mixtures thereof.